Artificial larynx



May 28,'1940Q R. R. RlEszl' 2,1202467- V Ammann mmm: Filed July 2s,r 195s z-sneets-sheet A1 ay I Tron/wk.

` rMay 2s, 1940; R.` Rimasi A uu'n'rcru.. LARYNx Filed July 2s, 195s f 2 sneetsshet 2 K- By -Patented May uNiTED #STATES PATENT- oFFicI-z v f asomar tobert lt. Riesa, Mount Vernon, N. Y., asllnwr to Bell/Telephone New York, N. Y.,

Laboratories, Incorporated. e acm-poration Aof New -York Application Jlyzs, ma ser-mno.- sznoi 11u omni.

l be generally satisfactory and commercially acceptable.they-shou1d be as small and as inc onspicuous as possible. 'Ihe size of the larynx tone generating or producing member or diaphragm, ofthe chambers associated with the dil aphragm, and of the driving mechanism-are fac- A large diaphragm is desirable because of the large amount of fluctuating air new that must be pumped out of and sucked'into the mouth' small diaphragm vibrate with a large amplitude. Inv laccordance with the invention.,amarkedre duction -in size may be obtained if several diaphragms'are made to vibrate in -phase and to pump air into and out of the larynx mouth tube. A single diaphragm Amay be replaced by two dlaphragmsu that move to and from each other in synchronism and vibrate with the same am-f 'plltude as the single diaphragm, each diaphragm having a diameter .707 times that of the single diaphragm; the chambers associated with thel two diaphragms may be made more shallow; and 'the diaphragms may be coil driven or` electroy magnetically driven in accordance with this in- 35 vention.

. i Another object, therefore,- is to reduce the 4size, simplify the structure and increase the efficiency of the artificial larynx, particularly of the electrical type. g v

'4.0.` A feature of the invention comprises fan artifi-l cial larynx comprising a' plurality of larnyx tone producingfor generating members or diaphragms. Another feature comprises s uch a larynxin bwhich. the ,diaphragms move toward and away ,43 from each other infsynchronism.

Still another feature comprises such a larynx in which the diaphragms are driven by coils attached thereto anddisposedin suitable magnetic air-gaps. y

A further feature comprises such a larynx in which'the diaphragms are tunedv to the same or different frequencies. .f

Another feature Acomprises an artificial larynx comprising an acoustical system having the '55 characteristics of a band pass filter."

tube of the larynx and the difficulty of 'makinga i of Fig. 6;

Other and'further'features will lue-'apparent from the description that follows hereinafter. A more complete understanding of this inven-r tion will be obtained from y'the following detailed description, read with reference to the appended l drawings. wherein: i.

Fig. 1 is a cross-sectional view of an electrical artificial larynx embodying the invention;

. Fig. 2 is a schematic diagram of a' circuit for thedevice of Fig-1;v l Figs. 3- and 4 'show' alternative arrangementsA for actuating or vibrating vthe larynx tone gen- -erating members or y,diaphragmm Fig. 5 represents 'an electric circuit analogue of the acoustical system of the device of Fig. l; Fig. 6 is a cross-sectionalview. of another electrical artificial larynx embodying the invention: Fig. `7 represents an electric circuit analogue of the acoustical system of the device of Fig. 6.

Fig. 8-is a perspective view of the device shown ,n

in Fig. 1 with parts broken away to show internal structure;

Fig. 91s a similar perspective view of the device Fig. V10 isa simplification of Fis'. Ri, Rz and Sa: and' y Fig. 11 is the equivalent circuit of Fig. 10.

The ievice .of pag.1 is an electrical artificial larynx, designated generally as I0, comprising a v hollow enclosure, casing or shell I2, containing a 'pair ofspaced Alarynx tone 'producing members or diaphragms- M that lmay be'o'f metal and that divide the interior of the casing into a central air chamber I6 and outerair chambers The casing is provided with inwardlyprojecting tubular portions 2|l,connecting the chambers I8 with the air outside of the casing, and, with the chambers I8, proportioned so as to provide resonators on the outer sidev of each diaphragm that resonate at a frequency preferably between the first o andsecondharmonics of the associated larynx tone producing member-or diaphragm. The central chamber has an outlet constituted by the reentrant portion 2-2 of the casing, a mouth`tube 2l, for example, of hard'or soft rubber, providing a continuation ofthe tubular passage 26, whereby, when alarynx tone `is generated, it may be .introduced into-the users vocal cavities, there to be lmodulated as in the case of .natural speech. The diaphragms are vibrated, preferably, by electrodynamicnreans comprising annular coils 28 secured to but insulated from the inner sur- -ffaces of the diaphragms and disposed in the airgaps 30 in a permanent magnetl 32, suitably supported in the central chamber. The magnet may 5 omitting u be in two parts secured together at the portion intermediate the air-gaps by suitable fastening means, such as the vscrews 8|, the same portion containing a plurality' of drillings or passages 33,. connecting the cylindrical space within the magnet with the rest of the space constituting the chamber I8, the holes being sumciently large and numerous so that the chamber constitutes a single acoustical stiffness inthe frequency range of interest. .As shown in Fig. 2, the coils are connected in series with each other and with the circuit making and breaking contact 84, battery 38 and a circuit controlling switch 88. When the switch 38 is closed, current flows through the coils, and the interaction of the permanent mag-l net field and that developed by the current in f the coils causes the coils to move in the airphragms I4 with which they are associated, the

winding comprising the coil 28 on the diaphragm I4 which cooperates with contact 84 has one end electrically connected to said diaphragm. It is apparent,l a'soft iron magnetic structure withl a suitable magnetizing winding could besubstituted for the permanent magnet 32. The diaphragms, furthermore, may be .tuned to or made to have the same or different fundamental frequencies of vibration. In the arrangement of Figs. 1 and 2, the diaphragms move toward each other initially, the circuit is opened between a diaphragm and the contact 84, current ceases to ow in the coils, and the diaphragms return to their original positions,v which causes the circuit to be closed again -at the -contact 84, and the cycle is repeated; In this way, as long as the switch 38 is closed, the diaphragm are caused Ato vibrate and to generate a larynx tone that is introduced into the users vocal cavities through the tubular passagef28 and -the mouth tube 24.

F18. 1 is an electric circuitlanalogue of the acousticalsystem of the' device of Fig. 1. Mi. Ri' and S1 represent the acoustical mass, resistance and stiffness .of each diaphragm I4; Sz, the acoustical stillness of the chamber I8 on the outside surface of the diaphragm; and M1 and R2. the acousticaLmass and resistance of the tubular portion 28extending;intoz the chamber Sa represents the acoustical stiffness of the central chamber; Ma and'Rc, the acoustical mass and resistance of the outlet4 and mouthvtube; and E. the driving force exerted through each coil."l 4When the larynx is operated; the Vdriving forces tend to send current in' the directions indicated by the arrows so that' they. sendcurrents in phase4 through the shunt impedance. 'The energy dissi-v pated in the shunt resistance represents the useful sound energy thatfisf'introduced into the currents all ilow through the shunt impedance, attained by proportioning the elements of the filter to this end.

If Fig. 5 is simplified by omission of R1 and Rz and of Sa, th circuit of Fig'. 10 is obtained.

Since it is desired to have large currents flow in the shunt arm of Fig. 10, the useful frequency'range must fall within one of the theoretical attenuation bands of the filter. However, to have sistances, reflections occur that willv make the insertion loss depart widely from the theoretical attenuation. Thismust be taken into account in proportioning the parts of the larynx to insure that. in the useful frequency range, large currents flow in the resistance Ra so that maximum power is radiated into the mouth ofl the speaker,

The problem of satisfying this last condition can be simplified if we desire from Fig. 10 the vexactly equivalent circuit shown in Fig. 1l. Due.

to the symmetry of the system, no current flows across the line AB so that each filter is terminated in a resistance 2R3. 'Ihe elements of the filter `and the resistance 2R; must bevproportioned so thatthe resistance termination matches the illter impedance at some frequency within its passband. Since no current ows across the line AB, we are then certain that the lter elements can be proportioned so that, in the useful frequency range, large currents flow through the resistance 2R3.- o

Fig, 1, that of Fig. 3 or Fig. 4 may be used. In Fig. 3, armatures 48 are secured to the inner surfaces of the diaphragms I4, and an H-shaped, soft iron magnetic core 42 is disposed between the armatures. A magnetizing coil 44 is wound around the cross-bar 48 of the core, and is connected, as shown, in series with the switch 38, battery 38, and contact 34, one armature and diaphragm forming part of the current path. In Fig. 4, a pair of soft iron magnetic core members 48 and serially connected magnetizing coils El wound thereon, are disposed between the armatures 48. 'Ihe coils are connected in series with contact 34, battery 88 and switch 88. In the ar- 'diaphragm, armature, magnetizing coil, switch to battery. Current ow magnetizes the core and causes the armatures and consequently the diaphragms to be attracted to the cores. 'Ihe cir- Instead of the moving coil arrangement of 'rangements of Figs. 3 and 4, closure of switch 88 closesza circuit from battery through contact 84,v

cuit is. opened at contact 84, current ceases to flow, the cores demagnetize` and the armatures and diaphragms return to their original positions.

jThis closes the circuit Vagain and the cycle is re'- peated, and continues as long as the switchV 38 is closed, to produce a sustained tone.

The device of Fig. 6 is an electrical articial larynx, designated generally as88. It comprises an enclosure, casing or shell 8| comprisingl an annular central member or support 82 tothe opposite rim portions 84 of which diaphragms |4- are secured, for example, by cement. -The supporthas an inwardly extending tubular portion 88 connecting the chamber 88n with the air outside the casing. The tubular portion and chamber are proportionedso that together they constitute a resonator. resonating at a frequency in Fig. 7is an electriccircuit analogue ofthe acoustical system of the larynx of Fig'. 6. M1, Ri, S1 represent the acoustical mass, resistance and stiffness` of the diaphragms; S4, the acoustical stiffness of chamber 68; M4 and R4, the acoustical mass and resistance of the tubular passage of portion 66; S5, the acoustical stiffness of chamber 14; and M5 and Rs, the acoustical mass and resistance of the tubular passage 18 leading to theusers vocal cavities. In the frequency range of interest, that is, between about 100 and 3000 cycles per second, the front chamber sirnplifies to a resistance and an inductance, to-give a band ,pass structure with one passed band.

'I'he elements of the lter are proportioned so that the useful frequency range of the device falls in the region of attenuation. This may be explained in a manner similar yto that employed with respect to Fig. 5.

While this invention has been described with reference to specific embodiments thereof, it will be understood that it is not restricted thereto,

but is to be considered as limited only by th scope of the appended claims. i

What is claimed is: 1. An artificial larynx comprising a case, larynx tone generatingmembers in said case dividing it into three chambers, said members be- -v ing spaced apart to define one of said chambers between them, means for actuating said members, a tube from said-one chamber for conducting fthe' tone generated to the mouth cavity' of a user, and tubular means connecting each of the l v'other chambers with the atmosphere.

coil attached' to each member and magnetic structure containing air-gaps in whichsaid coils Lher, an H-shaped magnetic core between saidl lare disposed, a casing for said members and Vmeans, and means for conducting the tone produced by said members into the vocal cavities ofa user.

`3'. An artificial larynx comprising la casing,`a pair. of larynx tone producing members. means to cause said members to vibrate toward and away i'romeach other in synchronism, said means' comprising an varmature attached to each memarmatures. V and fa magnetizing winding around the cross-bar of the core, acasing for said members, and means for conducting the tone prof duced by said members into the vocal cavities of a user.

cured at its periphery at each endl of said support, the inner surfaces of said diaphragms delining-a sound chamber with said support, said .support havinga tubular portion connecting said-chamber with the outside air. and an' outer member forming around chamber with the 4. An larynx, comprising an annular" support, two diaphragms, each respectively seouter Asurfaces of said diaphragms, means for causing said diaphragms to generate a ylarynx tone, and means for conducting'said tone in to the vocal cavities of a user.

, 5. An artificial larynx comprising a pair of larynx tone producing diaphragms spaced apart to form a centralsound chamber, means forming an outer sound chamber on the outer side of each said diaphragms, tubular means connecting saidouter chambers with the outside air, and tubular means for conducting larynx tone from said central chamber to the mouth cavities of a user, said diaphragms, y`chambers and tubular means proportioned to constitute a band pass filter.

6. An artificial larynx comprising a pair-of diaphragms-,fspaced apart to form a sound chamber between their inner surfaces, a resonator on the outer surface of each'diaphragm, means for causing the diaphragms to generate a larynx tone, and means connected with the sound chamber forintroducing such toneinto a user's vocal cavities.

y'1. An artificial larynx comprisinga -pair of larynx tone producing members in a sound chamber and' spaced apart to form a second sound chamber between their inner surfaces, tubular means connecting said second sound chamber with the atmosphere, and tubular meansfor conducting the larynx tone from said firstmentioned. sound chamber into'a -users vocal cavities, said "members,` chambers and tubular means proportioned to constitute a band pass filter. Y

8. vAn artificiai larynx comprising a hollow enclosure, a pair of spaced larynx tone producing diaphragms in said enclosure dividing it into a aphragms and a second chamber, means con- '.necting one of said l chambers `with the out-- .side air, and-means for conducting larynx tone tone producing means, said tone producing means, sound chambers and outlets being proportioned to provide an acoustical system hav-v ingy the characteristics. of a band pass filter, the frequency range ofthe larynx region of-attenuation. l v

11. An artificial larynx comprising a casing, larynx tone producing diaphragms in said casfalling in Athe ing spaced apart toform-a soundchamber, a

coil attached to each diaphragm. a magnetic structure having air-gaps for said coils and having a central space extending between the diaphragms constituting -a parto! said chamber,

said structure containing a passage connectingsaid central space with the :est of said chamber,

and means for conducting larynx tones into' the vocal cavities of a user,

I ROBERT n. nmsz. 

